Mobile shredder

ABSTRACT

A shredder mounted on a heavy-duty carrier for shredding refuse spread on the ground such as in a land-fill dump. The shredder includes a frame structure mounted to the heavy-duty carrier, a rotating drum having a plurality of shredding elements mounted thereon, a fixed set of teeth cooperating with the rotating drum and a breaker bar assembly fixed to the shredder frame to partially cover the projected frontal area of the drum. The breaker bar assembly reduces the size of large refuse particles entering the shredder and prevents excessively large bundles of material from being pulled into the shredder all at once. Further, the breaker bar, in combination with the frame, creates a vacuum scoop tending to draw smaller refuse particles into the shredder.

United States Patent 1 Ford 451 NW. 26, 1974 MOBILE Sl-llREDDER [57] ABSTRACT [76] Inventor: Fred Avery P 49 Summit A shredder mounted on a heavy-duty carrier for Redlands, Cahf- 92373 shredding refuse spread on the ground such as in a [22] Filed; Jan. 11 1974 land-fill dump. The shredder includes a frame structure mounted to the heavy-duty carrier, a rotating pp -I 432,606 drum having a plurality of shredding elements mounted thereon, a fixed set of teeth cooperating with [52] CI 241/1013, 241/189 R 241/190 the rotating drum and a breaker bar assembly fixed to 51 Int. Cl. nine 21/02 t Shredder frame Partially Pmiected [58] Field of Search "241/1017 10] M 189 R frontal area of the drum. The breaker bar assembly 5 186 reduces the size of large refuse particles entering the shredder and prevents excessively large bundles of [56] References Cited material from being pulled into the shredder all at once. Further, the breaker bar, in combination with UNITED STATES PATENTS the frame, creates a vacuum scoop tending to draw a"? 2 4 i smaller refuse particles into the shredder. t 1' IC 3.662.962 5/l972 Cobey 24l/l01 M Primary Examiner-Roy Lake 14 Claims, 5 Drawing Figures Assistant E.\'aminerE. F. Desmond Attorney, Agent, or Firm-Lyon and Lyon l A Z0 /& \\V g 5 i j y 5 L I I 7? 55 4/) 24 70 92 l 7 \i I 52 v O a! 0 [J96 4 m2 1/ O o M 14 O 5! k l 94 PATENIEL unvzsmn 31.850; 37 5 sum 10? a v PATENTEL RSV 26 I974 sum 2 or 5 MOBILE SHREDDER The present invention is directed to a mobile shredder for shredding refuse and the like deposited on the ground.

The shredding of refuse has been found to be beneficial for the subsequent handling and stabilization of the refuse material. This is particularly true of landfill operations where refuse is deposited and later covered with soil. When refuse materal is properly shredded, the volume thereof may be reduced up to 50 percent. This volume reduction along with the resulting, more uniform particle size and overall homogeneity makes the refuse easier to handle and noticibly reduces the stabilization time of the resulting landfill. As a result, the costs associated with operating the landfill are reduced while the usefulness and consequently the economic value of the project is increased. In some instances, the shredded refuse tends to interlock thereby becoming less suseptible to being blown about. Consequently, the common and costly practice of spreading dirt each day over new refuse in a landfill operation may be eliminated.

In order that refuse may be shredded for landfill operations, it has been common practice to establish a refuse shredding station to which refuse is delivered, processed, and then removed to the landfill project. The stationary shredders located at such shredding stations generally employ a high speed rotating drum having either hammers or knives extending therefrom. When hammers are employed, a grate is normally associated with the hammers. The hammers impact the material, breaking it into particles small enough to pass through the grate and out of the system. When knives are employed, a stationary set of knives, or comb, may receive the rotating knives for shredding the refuse. Naturally, there are systems which combine the impact principle of the hammer mill and the cutting principle of the knife shredders. Such shredding stations require the additional steps in landfill operations of bringing the material to the station and subsequently taking it to the landfill project. This necessarily leads to added initial cost and operating expense.

Alternately. shredders have been mounted on heavy duty carriers. In this way. the shredder may be taken to the landfill project rather than the refuse to the shredder. The shredder may be driven over the deposited refuse and in this way bring about a reduction in the particle size of the landfill material. However, such systems have not been commercially pursued to any substantial extent because of substantial disadvantages inherent in such systems. Specifically, such systems have been unable to control the amount of material drawn into the shredder as the heavy-duty carrier drives over the piles of refuse. This is not true of shredding stations wherein refuse feed is easily controlled. This uncontrolled feed situation is aggravated by the tendency of the shredder to pull material into itself. As a result, the portable shredder quite often becomes jammed, overloaded or breaks down. Another problem is that the shredder must be designed to compromise between scooping up all of the refuse material and preventing the shredding elements from contacting the ground. Consequently, it is often necessary to set the rotating shredder at a position relative to the ground such that a substantial portion of the refuse is not processed.

The present invention is directed to a mobile shredder which may be used at a landfill site and which overcomes the feed problems heretofore experienced by such mobile shredders. The shredder of the present invention is mounted on a heavy-duty carrier. A breaker bar assembly is provided on the front side of the shredder to partially cover the anterior side of the shredder mechanism. This breaker bar assembly helps to control the feed to the shredder mechanism by breaking the large refuse particles and allowing a preliminary shredding before the refuse enters the main portion of the shredder. Further, the breaker bar assembly, in combination with the shredder frame, define a vacuum scoop which enables the shredder to draw refuse material not intercepted by the rotating shredding elements into the shredder mechanism by means of a vacuum created by the rotating shredder mechanism.

Accordingly, it is an object of the present invention to provide an improved mobile shredder.

It is a further object of the present invention to provide a mobile shredder having a controlled refuse feed into the shredder mechanism.

It is another object of the present invention to provide a mobile shredder having a breaker bar assembly mounted to partially cover the anterior side of the shredding mechanism.

It is yet another object of the present invention to provide a mobile shredder having a vacuum scoop through which refuse is drawn.

Thus, a mobile shredder which may be employed at landfill projects is disclosed which controls the feed of refuse into the shredder mechanism. Other objects and advantages will become apparent from the description herein.

FIG. 1 is a side view of the mobile shredder shown operating over refuse.

FIG. 2 is a front view of the shredder taken along line 2-2 of FIG. 1.

FIG. 3 is a cross-sectional side view of the shredder mechanismtaken along line 33 of FIG. 2.

FIG. 4 is a cross-sectional elevation of the shredder mechanism taken along line 4-4 of FIG. 3.

FIG. 5 is a cross-sectional detail taken along line 5-5 of FIG. 4.

Turning specifically to the drawings, a heavy-duty carrier 10 is illustrated in FIG. 1. In the present embodiment. the heavy-duty carrier 10 includes a central portion designed for the suspension of equipment beneath the vehicle. The shredder mechanism, generally designated 12, is suspended beneath the heavy-duty carrier 10 by means of a pivot 14 and hydraulic cylinders 16. This mounting arrangement allows the shredder mechanism 12 to be raised or lowered relative to the heavyduty carrier 10 to prevent the shredder mechanism 12 from contacting the ground when going over rough terrain. A guard 18 is illustrated in the present embodiment as being provided on the front of the heavy-duty carrier 10. The guard 18 may be employed to push over small trees when the shredder is used for thinning and shredding orchards and the like.

The shredder mechanism 12 incorporates a support frame 20 best illustrated in FIGS. 2 and 3. The support frame 20 includes a box member 22 extending laterally across the upper anterior portion of the support frame 20. Side box members 24 extend substantially the length of the shredder mechanism 12 on either side thereof from the outer ends of the box member 22 to the pivot 14. Gussetts 26 strengthen the joints between the box member 22 and the side box members 24.

The support frame 20 further includes side panels 28 and 30. The side panels 28 and 30 depend from the side box members 24 to positions near the ground. The extension of the side panels 28 and 30 to positions near the ground helps to keep refuse picked up by the shredding mechanism from being thrown laterally from the shredder. A back panel 32 as seen in FIG. 3 extends between the side panels 28 and 30 to help direct shredded material toward the ground. A horizontal panel 34 extends rearwardly from the lower end of the back panel 32 to help contain shredded material on the ground and protect the aft portion of the heavy-duty carrier. A horizontal plate 36 also extends between the side panels 28 and 30 at the forward end of the shredding mechanism 12. The hydraulic cylinders 16 are attached to the shredder mechanism 12 at the horizontal plate 36 by lugs 38. Vertical support plates 40 help support the horizontal plate 36 about the hydraulic cylinder 16. The vertical support plates 40 extend upwardly to the box member 22.

A drum 42 is positioned on a substantially horizontal axis extending between the two side panels 28 and 30 below the main portion of the support structure 12. The drum 42 is exposed to the ground directly beneath the carrier for receiving refuse lying on the ground as the carrier 10 moves across the landfill site. The drum 42 is rotatively mounted to each of the side panels 28 and 30 by means of heavy-duty bearings 44. At one end, a pulley 46 is fixed relative to the drum 42 exterior to the side panel 28. Means are provided for forcibly rotating the drum through the pulley 46. A 400 horsepower engine (not shown in detail) powers a drive belt 48 which is tightly drawn over the drum pulley 46. The size of the engine employed to rotate the drum 42 is dependent upon the power requirements of the shredder. Specifically, the width of the shredder, the number and type of shredding elements, the material being shredded, and the speed at which the carrier is driven will all operate to establish the power requirements. A 400 horsepower engine has been found to be very suitable for the present embodiment as herein described. A clutch is employed with the engine to start the drum 42.

Shredding elements 50 are mounted about the drum 42 for performing the shredding operation. The shredding elements 50 are shown in the present invention to be fixed teeth. However, a plurality of shredding element configurations are compatible with the present system. A hammer mill arrangement may be employed wherein pivoted hammers replace the fixed teeth of the present embodiment. The pivoted hammers are held outwardly by centrifugal acceleration and tend to employ impact rather than shearing loads to shred the material. In the present embodiment, there are approximately 105 teeth located on an 8 foot drum in 6 rows. It is believed that the more teeth which can be employed, the better the shredding action. However, there isa limit to the number of teeth which may be placed on a given drum because of space considerations. The shredding elements 50 are also staggered in succeeding rows such that each succeeding row of elements 50 follows a path between the paths of the elements 50 of the preceeding row. This effect is shown in FIG. 4 wherein phantom shredding elements 52 are illustrated between the shredding elements 50. This staggered arrangement is employed in the present embodiment for ease of fabrication rather than for improved shredding. In the present embodiment, each shredding element is formed into a fixed tooth 50 having a hooked tip pointing in the direction of rotation. The hook is believed to help concentrate the initial force exerted by each tooth 50 against the refuse being shredded.

Each tooth 50 is mounted to the drum 42 between mounting plates 54 and 56. The mounting plates 54 and 56.are welded to the drum 42 in pairs for receiving each of the teeth 50. The mounting plates 54 and 56 are spaced approximately 1 inch apart which is the width of each of the teeth 50. Extending through each set of mounting plates 54 and 56 are dowels 58, and 62. The teeth 50 are profiled to receive the dowels 58 and 60 as best seen in FIG. 5. Each shredding element 50 may be threaded between the dowels 58 and 60 and then rotated into the position as shown in FIG. 5. A locking plate 64 is positioned behind each tooth 50 and ahead of the locking dowel 62. The locking plate 64 is prevented from moving away from the tooth 50 because of interference with the dowels 60 and 62. A locking bolt 66 extends through the locking plate 64 to engage a profiled notch 68 in the tooth 50. The locking bolt 66 is compressed against the tooth 50 thereby forcing the retention of the tooth 50 between the mounting plates 54 and 56. The locking bolt 66 also holds the locking plate 64 against the dowels 60 and 62. In this manner, each of the plurality of teeth 50 may be rigidly retained on the drum 42 and yet may be easily replaced when worn or damaged.

The overall diameter from tip to tip of the drum and teeth 50 is approximately 32 inches in the present embodiment. Including the drum 42, the shredding elements 50, the mounting plates 54 and 56 and the remainder of the teeth locking mechanisms, it is estimated that the overall drum weight is approximately 4 tons. The angular speed of the drum is maintained at approximately 1,000 rpm on the present device. A standard rule of thumb on tip speeds used in such devices is to maintain the tip speed between 5,000 and 10,000 feet per minute. It is believed that in the present invention, a tip speed in the neighborhood of 8,000 or 9,000 feet per minute is preferred. However, the system will operate at lower tip speeds.

The position of the drum and shredding elements relative to the ground is controlled by the hydraulic cylinders 16 as discussed above. It is preferred that the teeth 50 do not hit the ground during the operation of the unit. The operator of the carrier is able to keep the support frame 12 high enough above the ground by manipulation of the hydraulic cylinders 16 so that teeth 50 will be in the desired position relative thereto. The relative positioning of the drum 42 and the support frame 12 is such that in the present embodiment, the lower most travel of the teeth 50 is below the bottom edges of the side panels 28 and 30. This relationship is not critical and it is believed that the side panels 28 and 30 may extend to a position at or below the lower most travel of the teeth 50. It has been found beneficial to have the side panels 28 and 30 extend to prevent refuse from being thrown laterally from the shredding mechanism. At the same time, the side panels 28 and 30 should not extend so low that they will drag on the ground and prevent the teeth 50 from being properly positioned relative to the ground.

For cooperating with the teeth 50 to shred refuse,.

means are provided which are fixed to the support frame 12. In the present embodiment, stationary teeth 70 are arranged in two rows extending across the support frame to form two combs. To support the stationary teeth 70, each tooth 70 is welded to a stud 72 which is bolted to the support frame by means of bolts 74. This relationship is best seen in FIG. 4. The stationary teeth 70 are also supported from behind by means of triangular support blocks 76 and 78 which are welded to the support frame. The stationary teeth 70 are spaced approximately 1 inch apart are aligned with the teeth 50 such that the teeth 50 will pass between the stationary teeth 70. In this way, refuse brought to the stationary teeth 70 by the teeth 50 is torn and impacted into chunks which will fit between the stationary teeth 70. The clearance between the stationary teeth 70 and the several mounting plates 54 and 56 is kept to a practical minimum in order that the great majority of refuse will pass through the stationary teeth 70 rather than underneath. The centrifugal acceleration of the refuse as it is forced around the drum 42 by the rotating shredding elements 50 also operates to force the debris into a path which intersects the stationary teeth 70.

The stationary teeth 70 are fixed relative to a top plate 80 forming a part of the overall support frame 20. The top plate 80 is pivotally mounted to the side panels 28 and at pivots 82 as best seen in FIG. 3. The top plate 80 may be pivoted away from the shredding elements as seen in phantom in FIG. 3. A hydraulic ram 84 is pivotally mounted to the top plate 80 through mounting bracket 86 and is supported at its other end relative to the side box members 24 by a mounting plate 88 and lugs 90. A rod 92 accurately locates the top plate 80 when it is in the closed position. During operation of the shredding mechanism, the top plate 80 is forcefully held in position by the hydraulic ram 84. The top plate 80 is retractable from the drum for easy access to the drum 42, the teeth 50, and the stationary teeth 70.

A breaker bar assembly, generally designated 94, is positioned to partially cover the anterior projection of the drum 42 and teeth 50, as best seen in FIG. 3. A vertical plate 96 extends between the side panels 28 and 30 downwardly from the side box members 24. The horizontal plate 36 abuts the vertical plate 96 and is rigidly fixed thereto. The breaker bar assembly 94 further includes a guide plate 98 forming the furthermost portion of the shredder mechanism 12. The guide plate 98 is rigidly fixed to the horizontal plate 36 and extends downwardly to prevent refuse from building up on the vertical plate 96 and other members. The guide plate also extends at an angle downwardly and rearwardly to force refuse toward the lower side of the drum 42.

A heavy breaker bar 100 extends across the lower side of the shredder 12 substantially parallel to the axis of the drum 42. The breaker bar 100 forms an extension of the guide plate 98 and further forces refuse downwardly toward the lower portion of the drum 42 and teeth 50. The breaker bar 100 is of 1 inch steel plate to help break up large pieces of refuse before they can be entangled with the rotating drum 42 and to cooperate with the rotating teeth 50 to provide a preliminary shredding of the refuse. Support for the breaker bar 100 is provided by the vertical plate 96 and a support brace 102. The rearward edge of the breaker bar 100 is met by the vertical plate 96 which is slightly arcuate to provide clearance for the shredding elements 50. The junction between the vertical plate 96 and the breaker bar 100 is established, in the present embodiment, at approximately one inch from the path of the shredding elements 50.

The positioning of the breaker bar 100 results in a reduced entrance area leading to the rotating drum 42 and teeth 50 and provides a stationary structure near the rotating teeth 50 for effecting a preliminary coarse shredding mechanism for large refuse pieces. This reduced entrance area is capable of controlling the refuse particle size approaching the shredding mechanism. The positioning of the breaker bar 100 relative to the ground operates to provide a first sizing of the incoming refuse particles by crushing the refuse as the carrier passes. The reduced entrance area also tends to prevent large entangled masses of refuse from being drawn into the shredding mechanism all at once by providing efficient resistance to the flow of refuse to the drum and teeth that the masses will become disentangled.

The reduced entrance area determined by the lower edge of the breaker bar 100 and the ground is primarily established by the vertical setting of the entire shredder mechanism 12 relative to the ground. However, the position of the shredder mechanism is dependent upon the desired positioning of the teeth 50 relative to the ground. As the teeth are positioned as close as practical to the ground, the breaker bar will also be properly positioned. Further, as the shredder mechanism 12 is raised, the drum 42 is also raised. Thus, when the breaker bar 100 is up, the shredding elements 50 will contact only the upper portion of large refuse particles. It has been found that the vertical relationship between the drum and teeth and the breaker bar is acceptable for most operations when the breaker bar 100 covers the anterior projection of the drum 42 and teeth 50 to approximately the bottom of the drum 42 as best seen in FIG. 3.

The relative positioning of the breaker bar 100 and the teeth 50 further reduces the refuse particle size drawn upward to the stationary teeth 70. When refuse is encountered by the shredder mechanism 12 which is larger than the spacing between the drum 42 and the breaker bar 100, the teeth 50 tend to initiate a primary shredding at the location of the breaker bar 100. The entire mass of material will be forced upward by the rotating teeth 50. However, the breaker bar 100 will prevent such upward movement except by the portion of material which has passed the inner edge of the breaker bar 100. This action creates a preliminary shredding and disentangling of the refuse before it reaches the stationary teeth 70. The refuse which then reaches the stationary teeth will be of acceptable size and easily processed. It should be noted that the spacing between the breaker bar and the drum 42 is not affected by the position of the entire shredder mechanism relative to the ground. Consequently, the preliminary shredding action of the breaker bar 100 does not depend on the positioning of the support frame.

The breaker bar 100 is spaced from the tips of the rotating teeth 50 approximately one inch in the present embodiment. it is not essential that a one inch space be maintained. However, the closer the breaker bar is to the rotating teeth, the more preliminary shredding will occur. Therefore, the lower edge of the breaker bar 100 should terminate in a line near the tips of the teeth 50, less than around four inches in the present embodiment and preferably around one inch.

The breaker bar assembly 94, in combination with the side panels 28 and 30, further enchance this shredding operation through the creation of a vacuum scoop. The rotation of the drum 42 in the neighborhood of 1,000 rpm creates a vacuum at the leading side of the drum 42. The side panels 28 and 30 and the breaker bar assembly 94 in forming a closed structure about the drum 42 operate to enhance this vacuum. The vacuum created near the leading side of the drum 42 is of sufficient magnitude to draw refuse particles toward the rotating teeth 50. In this way, the shredder mechanism 12 may be set sufficiently above the ground to insure that the teeth 50 will not come in contact therewith and yet substantially all of the refuse lying on the ground will be drawn toward the stationary teeth 70 by the combined operation of the vacuum and the physical action of the teeth 50.

In summary, the overall system is operated by rotating the drum 42 at approximately 1,000 rpm. At the same time, the shredding mechanism 12 is positioned such that the shredding elements 50 will approach but will not contact the ground. The heavy-duty carrier is then moved forward to allow the shredder mechanism 12 to encounter and process the refuse laying on the ground. It has been found that on smooth ground the heavy-duty carrier may travel at speeds up to 20 mph. Naturally, with material which is extremely resistant to shredding, the carrier speed may be reduced to insure that the shredder mechanism 12 will not be overloaded.

Thus, a mobile shredder is provided which is capable of controlling the refuse input to the shredder mechanism. Further, a vacuum scoop is provided to help draw particles not positively contacted the rotating teeth 50 into the shredder. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein described. The invention, therefore, is not to be restricted except by the spirit of the appended claims.

What is claimed is:

l. A mobile shredder mounted to a heavy-duty carrier and comprising a support frame adjustably mounted to the heavyduty carrier;

a drum rotatably mounted to said support frame, the axis of said drum being substantially horizontal and said drum being exposed to the ground over which the carrier is directed;

means for forcibly rotating said drum;

a plurality of shredding elements mounted to said drum and extending outwardly therefrom;

means fixed to said support frame cooperating with said shredding elements for shredding material introduced to said shredder; and

a breaker bar assembly rigidly mounted to said support frame substantially parallel to the axis of said drum, said breaker bar assembly terminating at a line near the outermost path of said shredding elements.

2. The shredder of claim 1, wherein said breaker bar assembly terminates at a point approximately l inch from the extreme path of travel of said shredding elements.

3. The shredder of claim 1 wherein said breaker bar assembly partially covers the anterior projection of said drum.

4. The shredder of claim 3 wherein said support frame further includes side panels extending at either end of said drum to below said drum, said side panels and breaker bar assembly cooperating to form a vacuum scoop.

5. The shredder of claim 1 wherein said plurality of shredding elements are teeth fixed to said drum 6. The shredder of claim 1 wherein said breaker bar assembly includes a heavy steel plate forming the terminating line near the outermost path of said shredding elements.

7. A mobile shredder mounted on a heavy-duty carrier comprising a support frame adjustably mounted to the heavyduty carrier and including side panels extending downwardly from said support frame;

a drum rotatably mounted to said support frame, the axis of said drum being substantially horizontal and said drum being exposed to the ground over which the carrier is directed, said drum being positioned between said side panels;

means for forcibly rotating said drum;

a plurality of shredding elements mounted to said drum and extending outwardly therefrom;

means fixed to said support frame cooperating with said shredding elements for shredding material introduced to said shredder; and

a breaker bar assembly rigidly mounted to said support frame substantially parallel to the axis of said drum, said breaker bar assembly partially covering the anterior projection of said drum to provide in cooperation with said side panels a vacuum scoop for the attraction of light refuse into said shredder.

8. The shredder of claim 7, wherein said breaker bar assembly terminates at a point approximately 1 inch from the extreme path of travel of said shredding elements.

9. The shredder of claim 7 wherein said plurality of shredding elements are teeth fixed to said drum.

10. The shredder of claim 7 wherein said breaker bar assembly includes a heavy-duty steel plate forming the terminating line near the outermost path of said shredding elements.

11. A mobile shredder comprising a heavy-duty carrier;

a support frame adjustably mounted to said heavyduty carrier;

a drum rotatably mounted to said support frame, the axis of said drum being substantially horizontal and said drum being exposed to the ground over which said carrier is directed;

means for focibly rotating said drum;

a plurality of shredding elements mounted to said drum and extending outwardly therefrom;

means fixed to said support frame cooperating with said shredding elements for shredding material introduced to said shredder; and

a breaker bar assembly rigidly mounted to said support frame substantially parallel to the axis of said drum, said breaker bar assembly partially covering the anterior projection of said drum to reduce the entrance area to said drum.

12. The shredder of claim 11 wherein said breaker 14. The shredder of claim 11 wherein said support f ly termmates the outermost P of frame further includes side panels extending at either Shreddmg elements end of said drum to below said drum, said side panels 13. The shredder of claim 12 wherein said breaker d b k b b] bar assembly terminates at a point approximately one 5 an rea er ar assem y cooperatmg to for m a inch from the extreme path of travel of said shredding P- elements. 

1. A mobile shredder mounted to a heavy-duty carrier and comprising a support frame adjustably mounted to the heavy-duty carrier; a drum rotatably mounted to said support frame, the axis of said drum being substantially horizontal and said drum being exposed to the ground over which the carrier is directed; means for forcibly rotating said drum; a plurality of shredding elements mounted to said drum and extending outwardly therefrom; means fixed to said support frame cooperating with said shredding elements for shredding material introduced to said shredder; and a breaker bar assembly rigidly mounted to said support frame substantially parallel to the axis of said drum, said breaker bar assembly terminating at a line near the outermost path of said shredding elements.
 2. The shredder of claim 1, wherein said breaker bar assembly terminates at a point approximately 1 inch from the extreme path of travel of said shredding elements.
 3. The shredder of claim 1 wherein said breaker bar assembly partially covers the anterior projection of said drum.
 4. The shredder of claim 3 wherein said support frame further includes side panels extending at either end of said drum to below said drum, said side panels and breaker bar assembly cooperating to form a vacuum scoop.
 5. The shredder of claim 1 wherein said plurality of shredding elements are teeth fixed to said drum
 6. The shredder of claim 1 wherein said breaker bar assembly includes a heavy steel plate forming the terminating line near the outermost path of said shredding elements.
 7. A mobile shredder mounted on a heavy-duty carrier comprising a support frame adjustably mounted to the heavy-duty carrier and including side panels extending downwardly from said support frame; a drum rotatably mounted to said support frame, the axis of said drum being substantially horizontal and said drum being exposed to the ground over which the carrier is directed, said drum being positioned between said side panels; means for forcibly rotating said drum; a plurality of shredding elements mounted to said drum and extending outwardly therefrom; means fixed to said support frame cooperating with said shredding elements for shredding material introduced to said shredder; and a breaker bar assembly rigidly mounted to said support frame substantially parallel to the axis of said drum, said breaker bar assembly partially covering the anterior projection of said drum to provide in cooperation with said side panels a vacuum scoop for the attraction of light refuse into said shredder.
 8. The shredder of claim 7, wherein said breaker bar assembly terminates at a point approximately 1 inch from the extreme path of travel of said shredding elements.
 9. The shredder of claim 7 wherein said plurality of shredding elements are teeth fixed to said drum.
 10. The shredder of claim 7 wherein said breaker bar assembly includes a heavy-duty steel plate forming the terminating line near the outermost path of said shredding elements.
 11. A mobile shredder comprising a heavy-duty carrier; a support frame adjustably mounted to said heavy-duty carrier; a drum rotatably mounted to said support frame, the axis of said drum being substantially horizontal and said drum being exposed to the ground over which said carrier is directed; means for forcibly rotating said drum; a plurality of shredding elements mounted to said drum and extending outwardly therefrom; means fixed to said support frame cooperating with said shredding elements for shredding material introduced to said shredder; and a breaker bar assembly rigidly mounted to said support frame substantially parallel to the axis of said drum, said breaker bar assembly partially covering the anterior projection of said drum to reduce the entrance area to said drum.
 12. The shredder of claim 11 wherein said breaker bar assembly terminates near the outermost path of said shredding elements.
 13. The shredder of claim 12 wherein said breaker bar assembly terminates at a point approximately one inch from the extreme path of travel of said shredding elements.
 14. The shredder of claim 11 wherein said support frame further includes side panels extending at either end of said drum to below said drum, said side panels and breaker bar assembly cooperating to form a vacuum scoop. 